Compact optical virus detection analyzer of nano- and micro- size bio particles using light scattering and fluorescence

ABSTRACT

A Compact Optical Virus Detection Analyzer (COVDA) uses light scattering and fluorescence to detect nanometer (nm) and micrometer (um) sized particles, such as biological particles and can be used to detect viruses such as coronavirus including SAR-CoV-2 responsible for COVID-19, pollen and bacteria. It can be used for prescreening, rapid detection of suspicious people. COVDA involves experimental and theoretical methods for particle and virus detection using Tryptophan as a key biomarker. Light sources in compact units include lamps such as Xenon (Xe) lamp with narrow band filters, LEDs (such as AlN) or laser diode, Q switched and mode lock Lasers for nanosecond and picosecond pulses (such as Nd Yag/Glass, Ti sapphire with Harmonic generator) in blue from 400 nm to 500 nm to generate second harmonic generation (SHG) in KDP/BBO crystals to produce 200 nm to 250 nm emission, or green laser pointers at about 530 nm to get emitters with harmonic crystals at about 270 nm or LEDS from 230 nm to 300 nm for pumping the samples at 230 nm to 289 nm to pump tryptophan and light scatter of nanometer particles of virus. The ultra high power ns and ps lasers in mJ to J can level can be used to locate Bio virus bacteria clouds in free space to image and destroy and kill virus.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent ApplicationNo. 63/092,084 filed Oct. 15, 2020, the contents of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The invention generally relates to pathogen detection devices and, morespecifically, to a compact optical virus detection analyzer of nano- andmicro-size bio particles using light scattering and fluorescence.

2. Description of the Prior Art

During 2002-2003 coronavirus SARS-CoV infected about 8000 people withabout 10% fatality rate [9]. In 2012, more than 1700 people wereinfected by coronavirus MERS-CoV with about 36% fatality rate [10]. Thisyear, the ongoing outbreak of the coronavirus (SARS-CoV-2) disease, alsoknown as COVID-19 has affected 235 countries over the world and causedabout 1,070,000 deaths [11]. The coronavirus causes widespread diseases,threatens human health and causes economic loss globally [12]. What isneeded as the first line of defense against pathogens is a compact sizeanalyzer to detect the potential presence of the pathogen—virus. Anaffordable at-home rapid reliable testing device can significantlyincrease the testing volume and frequency, reduce burdens on the healthcare system, and may significantly increase the chance of earlydetection and improve patient management. Such devices should be able tomake rapid or even real-time, and yet reliable tests. It may evenrequire the sample collection process to be minimally uncomfortable.However, currently it does not appear that there are such commercialdevices available in the market.

The currently available diagnostic testing methods include moleculartest, e.g. reverse transcription polymerase chain reaction (RT-PCR),antigen test and antibody tests [10]. The testing time varies fromminutes to several days. The accuracy also varies [10, 11]. Themolecular test is accurate but may take several days. Usually the testsare carried out by trained professionals either at a testing site or aspecialized laboratory [12] though some tests involve at-home collection[10]. Testing is key to the disease control and economic recovery.Studies showed that for surveillance and mitigation, what matters mostis the frequency with which people are tested, and the speed with whichactions are taken on results [13]. Experts suggested that “frequenttesting of big groups of people may be the only way to stop this virus”,which may require people “to start accepting less accurate, widespreadtesting for groups” [13].

SUMMARY OF THE INVENTION

There is a current and future need to detect pathogens in situ to helphumans cope with the spread of disease. Disclosed is a compact, portaland affordable real-time optical unit for at-home screening of viruses,particularly the coronavirus, also known as SARS-CoV-2.

Disclosed, as first line of defense against pathogens, is a compact sizeanalyzer (Compact Optical Virus Detection Analyzer—“COVDA”) that useslight scattering and fluorescence to detect nanometer (nm) andmicrometer (um) sized particles, such as biological particles usinglight scattering and fluorescence signals to detect potential presenceof a pathogen—a virus. An affordable at-home and businesses rapidreliable testing device COVDA can significantly increase the testingvolume and frequency, reduce burdens on the health care system, and maysignificantly increase the chance of early detection and improve patientmanagement. Such COVDA devices should be able to make rapid or evenreal-time, and yet reliable testing. It may even require a samplecollection process to be minimally uncomfortable. Currently there are nosuch known commercial devices available in the market. The currentinvention uses the makeup of virus and bacteria that contain asignificant amount of Tryptophan as the key bio fingerprint marker fordetection and kill the bio media.

A multidisciplinary program based on well-known optical scienceapproaches is used to develop a compact, portal and affordable real-timeoptical unit for at-home screening of viruses, particularly thecoronavirus. The device uses optical spectroscopy and photonicstechnologies based on light scattering of small particles as well asmolecular fluorescence spectroscopy focusing on Tryptophan, one of thekey features and nanometer and micrometer size particles of the biomedia. One determines the size and emission of the virus and bacteria inspectral zone of 200 nm to 350 nm, in particular about 280 nm. Thefingerprint region is useful to detect and kill virus.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of the presentinvention will be more apparent from the description when taken inconjunction with the accompanying drawings, in which:

FIG. 1 is an artistic illustration of a transmission electron microscope(TEM) image of the coronavirus SARS-CoV2 structure, the spikes containtryptophan and other amino acids as listed in Tables 1 and 2;

FIG. 2 is a schematic block diagram of scattering and fluorescence inaccordance with the invention;

FIG. 3 is a graph showing the absorption spectra of Tryptophan withpeaks about 210 nm to 220 nm and 260 nm to 290 nm;

FIG. 4(a) is an illustration created of the virus by the CDC [1]; and4(b) is an enhanced TEM image of the coronavirus [3];

FIG. 5 is a schematic diagram that illustrates light scattering with aparticle at the origin, where I₀ is the incident light, I_(s) is thelight scattered at angles (θ, ϕ);

FIG. 6 are schematic diagrams that show scattering for particles ofdifferent sizes including (a) for small particles such as a virus, and(b) for larger particles such as pollen and dust;

FIG. 7 shows an example of a polar plot of scattered intensity vs.scattering angle for Mie scattering (λ=1 μm, r=1 μm) created usingMiePlot [4, 5];

FIG. 8 is a plot showing the intensity of white light as a function ofwavelength at a fixed scattering angle for a dispersion of 1.5 μmpolystyrene particles in water [2];

FIG. 9 shows a schematic diagram for the design and operation of thesystem (L: lens, BS: beam splitter, A: aperture, PD: photo detector, G:glass slide, UV: incident beam, I_(BS): backscattering, I_(FS): forwardscattering);

FIG. 10 shows the absorption spectra of Tryptophan in Fluorescence; and

FIG. 11 shows a spectral graph showing the absorption spectra oftryptophan fluorescence as shown in FIG. 10.

DETAILED DESCRIPTION

The COVDA system is an ideal candidate to meet the needs of wide andfrequent testing and ultrafast screening by the public. COVDA is basedon optical techniques that can be used to test a glass slide after aperson coughs or breaths on it to see if the person has a virus or infree space. Testing is based on the ratio of forward scatteringintensity (FS) and back scattering intensity (BS); the scatteringspectrum at a particular angle; and the fluorescence spectrum from keymolecular content of the Spikes and Internal make-up structure of thevirus such as amino acid Tryptophan and other UV spectral features. Thebio-media molecules can be excited by UV LEDs and detected by photonicsmethods. The optical light scattering and spectral methods would be“instantaneous” (low latency) with “point-of-test” results. If the virusis confirmed present, then the person can mail the sample to furthertest for confirmation.

The COVDA units developed in accordance with this invention is an idealcandidate to meet the needs of wide and frequent testing by the public.The first testing system based on optical spectroscopy techniques can beused to test a glass slide after a person coughs or breaths on it to seeif the person may have a virus. The testing is based on the 1) the ratioof forward scattering intensity (FS) and back scattering intensity (BS),2) the scattering spectrum at a particular angle, and 3) thefluorescence spectrum from key molecular content of the Spikes andInternal make-up structure of the virus such as amino acids, such astryptophan. The optical light scattering and spectral methods would be“instantaneous” (low latency) with “point-of-test” results. If the virusis confirmed present, then the person can mail the sample to furthertest for confirmation. Therefore, this invention, COVDA, is apre-screening technique, which will generate reliable negative results.The false positives will be referred to and verified in a medical labusing a standard technique such as PCR. This invention will use opticalspectroscopy and photonics technologies based on light scattering ofsmall particles as well as molecular fluorescence spectroscopy.

A Compact Optical Virus Detection Analyzer (COVDA) device will bedeveloped to rapidly detect viruses, including the coronavirus, based onthe elastic light scattering and fluorescence properties of the virus.An artistic illustration of SARS-CoV-2 particle is shown in FIG. 1. Themain innovations include (a) using ultraviolet (UV) in the range of200-300 nm and elastic light scattering to detect viruses including thecoronavirus based on their particle size and structure; and (b) usefluorescence of key biomolecules especially tryptophan (Trp) as abiomarker to detect coronavirus. Tables 1 and 2 show the absorptions andemissions of amino acids, and an estimate of each amino acid'scontribution to the total fluorescence of a covid particle, respectively[8].

TABLE 1 Absorption Fluorescence Wavelength Wavelength Quantum Amino Acid(nm) (nm) Yield Tryptophan (T) 280 348 0.20 Tyrosine (Y) 274 303 0.14Phenylalanine (F) 257 282 0.04

The breakdown of these amino acids in the viruses is shown in Table 1.Settled on fluorescence and found that Tryptophan, Tyrosine, andPhenylalanine are able to fluoresce. The absorption wavelengths,fluorescence wavelengths, and quantum yield for these amino acids.

TABLE 2 Approximate Approximate % of Amino Acid Constituent %Fluorescence Intensity Tryptophan (T) 2 30 Tyrosine (Y) 5 52Phenylalanine (F) 6 18

Table 2 contains the estimated contribution of each amino acid to thetotal fluorescence of the SARS-CoV-2 virus. There are substantialamounts of amino acids in the virus spikes.

The COVDA uses light scattering and fluorescence to detect nanometer(nm) and micrometer (μm) sized particles, such as biological particles.The COVDA can be used to detect viruses such as coronavirus includingSAR-CoV-2 responsible for COVID-19. This COVDA device will be used forprescreening, rapid detection of people and suspicious persons. Lightsources in compact units will be a lamp such as Xenon (Xe) lamp withnarrowband filters, AlN LEDs, or laser diode in uv, Nd glass/YAG ns/pslasers to generate second harmonic generation (SHG) in like KDP/bariumborate (“BBO”) crystals to produce 200 nm to 265 nm pumps for emission,or green laser pointers at about 530 nm to get emitters at about 265 nmor LEDs from 250 nm to 300 nm for pumping the samples, e.g. at 250 nm to289 nm to pump tryptophan and light scatter of nanometer particles ofvirus. The supercontinuum with SHG can be uses to pump the virus from210 nm to 300 nm

The invention involves several steps:

STEP #1—measure the ratio of forward scattering to backscattering(FS/BS) of 100-nm polystyrene beads that mimic the coronavirus. Aschematic block diagram of scattering and fluorescence units is shown inFIG. 2.

STEP #2—measure the fluorescence signal when the same 270-nm lightshines on the slide. The light intensity after a selected narrow-band(NB) filter, e.g.

˜340 nm is measured by a photo detector using filters and mini gratingspectrograph. This is to detect the fluorophores in the virus such astryptophan, lipids, proteins and RNA nucleotides. The whole spectrum ismeasured using a spectrometer in the advanced version usingsupercontinuum Q-switched nanosecond and picosecond with HG for 200 nmto 300 nm of the system. The absorption spectrum of tryptophan is shownin FIG. 3 showing 220 nm and 280 nm bands.

STEP #3—once the system is calibrated using the model samples, they aresent to be tested and evaluated for efficacy and detection sensitivityusing viruses such as SARS-CoV-2. FIG. 10 shows the absorption spectraof Tryptophan in Fluorescence; and FIG. 11 shows a spectral graphshowing the absorption spectra of tryptophan fluorescence as shown inFIG. 10.

In summary, the COVDA device can use both light scattering andfluorescence measurements to rapidly detect the coronavirus as apoint-of-care system for at-home use. This device may drastically changethe current testing situation for the coronavirus in the country thataffects the control of the virus, the reopening of businesses andschools, and the recovery of the economy.

Scattering Based Testing Analyzer

Coronavirus virions are spherical, 120-160 nm in diameter, with an outerenvelope bearing 20 nm-long club-shaped spike proteins that collectivelyresemble a crown or the solar corona [14]. Therefore, optical methodsmay be developed for detecting the virus based on the characteristic oflight scattering by the virus. An artistic illustration and atransmission electron microscope (TEM) image for the coronavirus areshown in FIG. 4(a) and FIG. 4(b), respectively, that show the 100-nmcentral sphere and the spikes. The main molecular content of the virusconsists of lipids, proteins, amino acids and RNA in a small nm size.When light encounters matter, various types of light-matter interactionsoccur. When light interacts with small particles, one of the mostimportant interactions is scattering. The process of light scatteringmay be considered as a complex interaction between the incidentelectromagnetic wave and the molecular/atomic structure of thescattering particles. A particle that is exposed to optical and UV lightcan be thought of as an optical antenna. The majority of light scatteredby the particle is emitted at the same frequency of the incident light,a process referred to as elastic scattering. There are mainly two lightscattering theory frameworks [15]. One is Rayleigh scattering (afterLord Rayleigh) that was originally formulated to be applicable to smalldielectric (non-absorbing) spherical particles. The second one is Miescattering (after Gustav Mie) or Lorentz-Mie scattering that providesthe general spherical scattering solution (absorbing or non-absorbing)without a particular bound on particle size. Therefore, Mie theory hasno size limitations and converges to the limit of geometric optics forlarge particles as well as Rayleigh scattering for small particles. Mietheory may be used for describing most spherical particle scatteringsystems, including Rayleigh scattering.

The size parameter of a particle is defined to be x=2πa/λ=ka, where a isthe radius of the spherical particle, λ is the wavelength of the lightin the medium. Therefore, λ=λ₀/m₀, λ₀ is the wavelength in vacuum andm₀=n₀−ik₀ is the complex index of refraction of the surrounding medium.In contrast, m_(p) is the complex index of refraction of the particle,with m_(p)=n_(p)−ik_(p). Here n is the ordinary refractive index withn=v/c; v and c are the speeds of light in the material and in vacuumrespectively; k is related to absorption. If the absorption is ignoredin the problem and the medium is air, we have k=0, m=n, m₀≈1, and λ≈λ₀.The value of x describes the size of the particle relative to thewavelength.

When the particles are much smaller than the wavelength, with x<<1,Rayleigh scattering theory can be applied. For example, when visiblelight is scattered by air molecules, it follows Rayleigh scattering. Thescattered light is the same for any azimuthal angle ϕ for a particularscattering angle θ, meaning the scattering is rotationally symmetricalaround the axis at forward direction. As indicated in FIGS. 5 and 6, theintensity I_(s) of light at scattering angle θ integrated over 2πazimuthal angle ϕ scattered by a small spherical particle of radius aand refractive index n from a beam of unpolarized light of wavelength λand intensity I₀ is given by

$I_{s} = {{I_{o}\frac{8\pi^{4}a^{6}}{r^{2}\lambda^{4}}\left( \frac{n^{2} - 1}{n^{2} + 2} \right)^{2}\left( {1 + {\cos^{2}\theta}} \right)} = {I_{o}\frac{x^{6}\lambda^{2}}{8\pi^{2}r^{2}}\left( \frac{n^{2} - 1}{n^{2} + 2} \right)^{2}\left( {1 + {\cos^{2}\theta}} \right)}}$

where r is the distance to the particle. The forward and back scatteredlight intensities are the equal. According to Rayleigh scattering, whenthe particle size increases with respect to the wavelength, thescattered light intensity increases.

If the particle size becomes comparable to wavelength of light, theforward-scattered light becomes stronger than back-scattered light. Inthe meantime, the peak polarization decreases and shifts to largerangles. The Mie scattering theory is needed to describe the scattering.

As the size increases further, the asymmetry in the scatted wave becomesmore pronounced and dominant forward scattering lobe narrows. If thelight with wavelength of ˜270 nm interacts with the coronavirus, thelight scattered by the central sphere of ˜100 nm is expected to followMie scattering, while the interaction with the spike proteins isexpected to follow Rayleigh scattering limit. When the distance r islarge compared to the wavelength of light, the interaction can bedescribed by Fraunhofer diffraction theory [16]. In this case, thescattering due to a particle is similar to the diffraction due to asingle aperture. The first order of destructive fringe for thediffraction can be found approximately at angle θ_(s)≈λ/a for smallangles. A small particle with respect to wavelength scatters light intoall angles while a large particle mainly scatters light forwardly. AsFraunhofer diffraction indicated, for smaller particles, the zerothorder bright fringe becomes wider, the first dark fringe is found at alarger angle, meaning the light is scattered into a larger angle.Schematic diagrams in FIG. 6 show light scattering with particles ofdifferent sizes.

If the particle further increases and becomes large relative to thewavelength of the light, Mie scattering converges to geometric opticsand the interaction may be interpreted in terms of refraction.

Mie theory starts from Maxwell's equations for an electromagnetic fieldand results in an exact description of the field when an interactiontakes place between the light and small particles. In the far-field zone(i.e., at the large distances r from a sphere), for a spherical particlescatterer, the amplitudes of the scattered wave is [15]

$\begin{pmatrix}E_{}^{s} \\E_{\bot}^{s}\end{pmatrix} = {\frac{e^{{ik}{({r - z})}}}{ikr}\begin{pmatrix}{S_{2}(\theta)} & 0 \\0 & {S_{1}(\theta)}\end{pmatrix}{\begin{pmatrix}E_{}^{i} \\E_{\bot}^{i}\end{pmatrix}.}}$

The Mie scattering amplitudes S₁(θ) and S₂(θ) are

${S_{1}(\theta)} = {\sum\limits_{n = 1}^{\infty}{\frac{{2n} + 1}{n\left( {n + 1} \right)}\left\lbrack {{a_{n}{\pi_{n}\left( {\cos\;\theta} \right)}} + {b_{n}{\tau_{n}\left( {\cos\;\theta} \right)}}} \right\rbrack}}$${S_{2}(\theta)} = {\sum\limits_{n = 1}^{\infty}{\frac{{2n} + 1}{n\left( {n + 1} \right)}\left\lbrack {{b_{n}{\pi_{n}\left( {\cos\;\theta} \right)}} + {a_{n}{\tau_{n}\left( {\cos\;\theta} \right)}}} \right\rbrack}}$where${\pi_{n}\left( {\cos\;\theta} \right)} = {\frac{1}{\sin\;\theta}{P_{n}^{(1)}\left( {\cos\;\theta} \right)}}$${\tau_{n}\left( {\cos\;\theta} \right)} = {\frac{d}{d\;\theta}{P_{n}^{(1)}\left( {\cos\;\theta} \right)}}$

where P_(n) ¹ are the associated Legendre polynomials, and parametersa_(n) and b_(n) are

$a_{n} = \frac{{m\;{\Psi_{n}({mx})}{\Psi_{n}^{\prime}(x)}} - {{\Psi_{n}(x)}{\Psi_{n}^{\prime}({mx})}}}{{m\;{\Psi_{n}({mx})}{\xi_{n}^{\prime}(x)}} - {{\xi_{n}(x)}{\Psi_{n}^{\prime}({mx})}}}$$b_{n} = \frac{{{\Psi_{n}({mx})}{\Psi_{n}^{\prime}(x)}} - {m\;{\Psi_{n}(x)}{\Psi_{n}^{\prime}({mx})}}}{{{\Psi_{n}({mx})}{\xi_{n}^{\prime}(x)}} - {m\;{\xi_{n}(x)}{\Psi_{n}^{\prime}({mx})}}}$

where m is the relative complex refractive index m_(p)/m₀ or n_(p)/n₀for non-absorbing case, Ψ and ξ are related to spherical Besselfunctions. The scattered intensities are proportional to the squares ofthe absolute values of these amplitudes.

Therefore, the scattered light intensity is a function of angle,wavelength, as well as the relative refractive index and size of theparticles. The particle scatters the light of a particular wavelengthinto different directions. The angular distribution of the scatteredwave is affected by the particle size very sensitively, which providesmeans of evaluating particle size based on light scattering. An examplepolar plot of scattered wave due to Mie scattering is shown in FIG. 7.

For a particular type of particle, the size of particle can be evaluatedor obtained based on the angular distribution of scattered light of aparticular wavelength. The laser diffraction (LD) technique measures thescattering of a fixed frequency of light over a range of angles [16,17]. For simplicity, in this invention, we measure the ratio between twoangles such as FS and BS to evaluate the particle size. The ratio of theFS at 0° and BS at 180° is [15]

$\frac{FS}{BS} \approx {1 + \frac{4{x^{2}\left( {m^{2} + 4} \right)}\left( {m^{2} + 2} \right)}{15\left( {{2m^{2}} + 3} \right)}}$

where m and x are defined above. To avoid incident light, measurementcould be taken at a small angle off 0° for FS.

Since the scattering is also a function of the wavelength, the particlesize can also be evaluated based on the spectral distribution of thescattered light, i.e. scattering spectrum collected at a particularscattering angle [18]. An example scattering spectrum due to 1.5 μmpolystyrene particles in water is shown in FIG. 8 from 200 nm to 1200nm. Alternatively, discrete wavelengths of the scattered light can bemeasured at a particular angle to evaluate the particle size forsimplicity. A supercontinuum laser or uv lamp can be used forscattering.

If there are particles of multiple sizes, the observed measurement ofintensity can be deconvoluted into sets of particle sizes that couldhave produced the result which is an ill-posed problem. A multivariateanalysis algorithm such as nonnegative matrix factorization (NMF) [19,20] may be used for the linear unmixing.

The scattered light may also be used to obtain further information aboutthe virus [21]. One of the important features of the coronavirus is thepresence of a certain number of spike proteins on its surface, formingaround the virus a kind of solar corona [22]. Using these spikes, thecoronavirus enters host cells. The number of the spike proteins is anindicator of the degree of danger of a given set of virions [23]. It hasbeen shown that the scattered light intensity and polarization as afunction of scattering angle and wavelength for a particular size ofmodel coronavirus particle are also affected by the number of spikes onthe particle [21]. Therefore, the number of the spike proteins as wellas the virion structure may also be evaluated based on thecharacteristics of the scattered light [21].

COVDA Fluorescence Based Testing Analyzer

Another specific optical spectroscopy photonic method for COVDA used todetect the coronavirus using the invented analyzer system is based onfluorescence. We have used native fluorescence (commonly noted asautofluorescence) and Raman spectroscopy to detect cancers [24-27] andbacteria [28] from molecules inside the species.

In biological samples, there are various key fluorophores that canprovide fluorescence signal, such as tryptophan [29, 30], proteins,lipids [31], nucleotides [32] etc. Since the coronavirus is made up ofRNA nucleotides, proteins and lipids [33], it can potentially bedetected using fluorescence techniques [24, 25]. In particular, thespike protein (characteristic SARS-CoV-2 structure) has a tryptophanrich N terminal region [34]. The excitation and emission peaks oftryptophan (Trp) are ˜270 nm, ˜340 nm, respectively [30]. This Trpspectral feature is a key fingerprint to emit light about 340 nm uponexcitation from 250 nm to 290 nm detecting a sample that maybe loadedwith SARS-CoV-2.

In this invention, a COVDA device uses light scattering and fluorescenceproperties of the virus. A schematic diagram of one embodiment of thedevice in accordance with the invention is shown in FIG. 2 for thedesign of the device, and FIG. 9 shows the light paths for scatteringwith the virus.

In this invention the COVDA systems implement the following:

1. The system is set up to measure the ratio of forward scattering tobackscattering (FS/BS) of 100-nm polystyrene beads that mimic thecoronavirus. As shown in FIG. 9, a 250-nm and a 270-nm UV LEDs as wellas Xenon Lamp 150 nm-400 nm light sources or supercontinuum laser sourcewill be used in the system. The fourth harmonic of NIR laser from 1064from Q switched Nd Laser at about 10 nsec or the second harmonic ofsecond harmonic from NIR laser for field at 265 nm. The LED light willbe converged using a positive lens. The beam goes through a beamsplitter, and strike on the particles on an anti-reflection (“AR”)coated beam glass slide. The glass slide is tilted at an angle, e.g.10-20°, so that the small amount of reflected light will be directedupwards (as indicated in the figure). The directly backscattered lightgoes back and is reflected by the beam splitter downwards (as indicatedin the figure) and then collected by a photo diode. The forwardscattered light passes the glass slide, and continues towards anotherphoto diode, which is placed at an angle slightly off 0° such as 5° toavoid direct incident beam. The FS/FS ratio formula will also becorrected from the equation shown above. In fact, a simplified versionof the detection system can also perform the measurement at anotherscattering angle without using the beam splitter. The FS/BS ratio can bemeasured for different particle size for comparison. This way, theunknown particle size can be compared and estimated based on theexperimental FS/BS ratio curves.

In the meantime, intensity ratio at each angle is obtained between thetwo wavelengths. Similarly, the ratio for different particle size can beobtained and used to estimate the particle size. If there are varioustypes of particles with different sizes, the whole spectrum of thescattered light can be measured and deconvoluted to retrieve the sizedistribution. A spectrometer can be integrated into an advanced versionof the system to measure the spectrum of the sample to determine thesize of the particles.

Light sources in compact units will be either a lamp such as Xe withnarrow band filters, AlN LEDs, or laser diode, high power ns/ps lasersource to generate SHG in like KDP, BBO crystals to produce 200 nm to250 nm emission, and green laser pointers at about 530 nm to getemitters at about 270 nm, or LEDS from 250 nm to 300 nm for pumping thesamples at 250 nm to 289 nm to pump tryptophan and light scatter ofnanometer particles of viruses.

The system measures the fluorescence signal when the same 270-nm to 290nm AlN LEDs light or laser diode and SHG crystal shines on the slidewith nm and um particles The light intensity after a selectednarrow-band filter, e.g. ˜340 nm is measured by a photo

Once the system is calibrated using non-virus nanoparticles, it can besent for testing. It will first be tested in a collaborated BLS-2 labfor detection of inactivated coronavirus. After that, the device will besent to a BSL-3/4 (i.e. P3/4) lab for final testing for coronavirus.

The invention, a compact UV LED analyzer COVDA ratiometer, can be usedto rapidly detect viruses, such as the coronavirus, based on the elasticlight scattering and fluorescence properties of the virus. Morespecifically, this compact optical analyzer device will be able to (a)detect 100-nm particles (e.g. polystyrene beads) that mimic coronaviruson an anti-reflection (AR) coated glass slide using appropriate lightsources with a wavelength within 200 nm-300 nm based on the ratio offorward scattering and backscattering (angular dependence) as well asscattering spectrum (wavelength dependence); (b) detect fluorescencesignals of tryptophan, proteins, lipids and mixture of nucleotides with270-nm LEDs. Light sources in compact units will be either a lamp suchas Xe with narrow band filters; or laser diode in blue from 400 nm to500 nm to generate SHG in like BBO crystals to produce 200 nm to 250 nmemission, and green laser pointers at about 530 nm to get emitters atabout 270 nm; or LEDS from 250 nm to 300 nm or harmonic from Q switchedlaser at about 265 nm for pumping the samples at 250 nm to 289 nm topump tryptophan and light scatter of nanometer particles of virus.

A diagnostic assay for SARS-CoV-2 should be capable of distinguishingamong the common upper respiratory viruses that could potentiallydisplay cross-reactivity with SARS-CoV-2, including flu viruses andRhinoviruses, responsible for the common cold. The coronavirus such asSARS-CoV-2 has a particle size of 20-200 nm, which can be measured byelastic light scattering. The spike protein (characteristic coronavirusstructure) has a tryptophan (Trp) rich N terminal region. The excitationand emission peaks of Trp are ˜270 and ˜340 nm, respectively. This Trpspectral feature is a key fingerprint to detecting the sample that maybeloaded with SARS-CoV-2. It should be noted, however, that this assaywill not distinguish between SARS-CoV-2 and the presence of other humanCoronaviruses that cause the common cold due to their structural andbiochemical similarities. Thus, a positive test result, in the absenceof symptoms specifically associated with COVID-19, would require furtherconfirmation. That being said, the proposed assay instrument could beused to distinguish SARS-CoV-2 infection from flu or Rhinovirusinfections due to fundamental differences in their structural andbiochemical parameters that can be detected by UV elastic lightscattering and fluorescence spectra that are capable of distinguishingamong the structural/biochemical properties of the different virusFamilies.

This compact Optical Virus Analyzer Device (COVDA) will be used as apoint-of-care system for at-home use. When deployed, the system will useboth light elastic scattering and fluorescence spectroscopy to detectthe virus. Once a signal from the slide with particles from human breathor saliva is detected with particle size being 100 to 200 nm andexpected fluorescence spectra, the slide can be sent to a lab to befurther tested for confirmation. Therefore, this invention will serve asa pre-screening technique, which will generate reliable negativeresults. The false positives can be verified in a lab using standardmethod such as PCR.

This invention can drastically change the current testing situation forthe coronavirus in the country which is affects the control of thevirus, the reopening of businesses and schools, and the recovery of theeconomy.

The foregoing is considered as illustrative only of the principles ofthe invention. Further, since numerous modifications and changes willreadily occur to those skilled in the art, it is not desired to limitthe invention to the exact construction and operation shown anddescribed, and accordingly, all suitable modifications and equivalentsmay be resorted to, falling within the scope of the invention.

1. An optical bio particle detection analyzer comprising a UV lightsource for generating a beam of light; a transparent sample holderpositioned in the path of said beam of light and adapted to support asample that may contain bio particles sought to be detected exposed tosaid beam of light; optical components for generating forward scatteringlight passing through said sample holder and for generatingbackscattering light after the sample is exposed to said beam of light;first photodetection means for detecting said forward scattering light;second photodetection means for detecting said backscattering light; andmeans for establishing the size of bio particles by comparing saidforward scattering and backscattering lights.
 2. The optical bioparticle detection analyzer defined in claim 1, wherein said lightsource is selected to detect bio particles within the nm and μm sizerange using scattering or fluorescence.
 3. The optical bio particledetection analyzer defined in claim 2, wherein said light source isselected to detect bio particles within the size range of 20-200 nm. 4.The optical bio particle detection analyzer defined in claim 2, whereinsaid light source uses fluorescence to detect nm and μm sized particlesfrom amino acid molecules in particles such as tryptophan.
 5. Theoptical bio particle detection analyzer defined in claim 1, wherein saidlight source uses ultraviolet (UV) light within the range of 200-300 nmfrom LEDs (Light Emitting Diodes), like AlN, laser diodes and/or HIGHPOWERglass or YAG with harmonic generation laser beams from solid statelasers to detect nano and micro particles from light emitted orscattered.
 6. The optical bio particle detection analyzer defined inclaim 1, wherein said light source is selected to detect Tryptophanfluorescence as a bio marker from a sample from a human person or animalto detect presence of viruses and/or bacteria from saliva, spit, blood,or breath from lung applied to said sample holder.
 7. The optical bioparticle detection analyzer defined in claim 1, wherein said means forestablishing uses a forward to back scattering ratio to detect nano andmicro particles.
 8. The optical bio particle detection analyzer definedin claim 1, wherein said light source is selected to detect bioparticles within the nm and μm size range uses angular pattern ofelastic light scattering to detect nano and micro particles.
 9. Theoptical bio particle detection analyzer defined in claim 1, wherein saidlight source is selected to detect 20 nm spikes on bio particles withinthe nm and μm size range to detect viruses, such as coronavirusesincluding the coronavirus SARS-CoV-2.
 10. The optical bio particledetection analyzer defined in claim 1, wherein said light source isselected to use fluorescence to detect viruses, such as coronavirusesincluding the coronavirus SARS-CoV-2 from tryptophan and other moleculesin a virus structure and makeup of proteins and lipids.
 11. The opticalbio particle detection analyzer defined in claim 1, wherein said lightsource is selected to combine both elastic light scattering andfluorescence to detect nm and μm sized particles including viruses,bacteria, and pollens.
 12. The optical bio particle detection analyzerdefined in claim 1, wherein said light source provides visible lightfrom 300 nm to LEDs 600 nm to detect molecules including collagen, NADH,flavins molecules in cells.
 13. The optical bio particle detectionanalyzer defined in claim 1, wherein said photo detectors are selectedto use fluorescence from tryptophan in a spike of a virus as afingerprint with excitation at 230 nm to 300 nm to detect emission inthe range of 320 nm to 340 nm from tryptophan as a key marker.
 14. Theoptical bio particle detection analyzer defined in claim 1, wherein saidlight source comprises a lamp, such as Xe, with narrow band filters, AlNLEDs or laser diode, or Q-SWICHED Nd YAG/glass laser ns/ps pulsed beamto generate SHG in KPD/BBO crystals to produce 200 nm to 250 nmemission, and green laser pointers at about 530 nm to get emitters atabout 270 nm and LEDS from 250 nm to 300 nm for pumping the samples at250 nm to 289 nm to pump tryptophan and light scatter of nanometerparticles of viruses.
 15. The optical bio particle detection analyzerdefined in claim 1, wherein said optical components include a beamsplitter between said light source, said sample holder being offset atan angle from a direction normal to a direction of propagation of saidbeam of light.
 16. A method of detecting optical bio particlescomprising the steps of generating a beam of light; positioning atransparent sample holder in the path of said beam of light and adaptedto support a sample that may contain bio particles sought to bedetected; exposing bio particles on said transparent sample holder tosaid beam of light; using optical components generating forwardscattering light passing through said sample holder and generatingbackscattering light when the sample is exposed to said beam of light;detecting said forward scattering light; detecting said backscatteringlight; and establishing the size of bio particles by comparing saidforward scattering and backscattering lights.
 17. The method ofdetecting optical bio particles as defined in claim 16, wherein saidforward scattering and backscattering light assume different angles ofpropagation and the particle size of the bio particles is determined bymeasuring a ratio of the angles of the forward and backscattering lightsrelative to the direction of propagation of said beam of light.
 18. Themethod of detecting optical bio particles as defined in claim 16,wherein the wavelength of said beam of light is selected to be withinthe range of 200-530 nm.
 19. The optical bio particle detection analyzerdefined in claim 1, wherein at least one of said first and secondphotodetector means comprises a photodetector used to detect the biovirus of bacteria agents cloud are uv sensitive for time delay imagingand spectral analyzers using selected optical filters or spectrometer todetect the virus/bacteria molecules,
 20. The optical bio particledetection analyzer defined in claim 1, wherein Time resolved timing ofthe pulse from emitted cloud can be resolved using remote time delaytime T=2 L/c is time to measure the cloud region and extend at distanceL away where c is speed of light.
 21. The method of detecting opticalbio particles as defined in claim 16, wherein Q SWITCHED NS/PS MODELOCKED LASERs (Nd-YAG/GLASS LASER, Ti sapphire) with harmonic generatorsare used to create high power uv in the range 200 nm to 300 nm—nominalat 280 nm with pulse energy>mJ to destroy and kill the virus in freespace and on surfaces.